1. Field of the Invention
The present invention relates to a tray conveying apparatus and method, and more particularly, to an apparatus and method for removing deficient components or parts and replacing these deficient components or parts with satisfactory parts in accordance with inspection results in an external appearance inspection system for semiconductor parts (semiconductor packages, etc.).
2. Prior Art
Various types of manufacturing apparatuses and inspection apparatuses are used in manufacturing processes for semiconductor components or semiconductor parts. In such apparatuses, the semiconductor parts are generally held in a row on trays and are supplied and conveyed in tray units.
For example, in the final process in semiconductor manufacturing, a package external appearance inspection apparatus is utilized, and the external appearance of the respective packages held on the trays is inspected by means of this apparatus. Afterward, the trays are fed to a tray conveying apparatus which is linked to the inspection apparatus. In addition to the function of conveying trays, this tray conveying apparatus has the function of replacing deficient parts (defective parts and reclaimable parts (semi-defective parts), etc.) with satisfactory parts. In other words, based on the external appearance inspection results, deficient parts are removed from the trays, and the trays are replenished instead with satisfactory parts that have been prepared beforehand. After it has thus been insured that the packages on the trays consist exclusively of satisfactory parts, the trays filled with satisfactory parts are conveyed to an unloader stacker, and the respective trays are stacked in a stack configuration.
FIG. 14 is a diagram which shoes an example of one of the above-described trays 10. This tray 10 has a plurality of pockets, and a semiconductor part is accommodated in each of these pockets 12. Various types of trays other than the tray 10 shown in FIG. 14 may be used.
FIG. 15 shows one example of a conventional package external appearance inspection system. This system is constructed from an in-tray type inspection apparatus 16, which performs an inspection of the external appearance of the parts while the respective parts are accommodated in the trays, and a conveying apparatus 14, which conveys the trays in which the parts whose external appearance has been inspected are accommodated. FIG. 15 shows the appearance of the conveying apparatus 14 as seen from above.
In FIG. 15, the conveying apparatus 14 is constructed from a conveying section 17 which conveys inspected trays 10D that have been discharged from the inspection apparatus 16, an unloader staker 18 which is installed on the rear stage of the conveying section 17, a first sliding mechanism 20 which causes a table 20A on which a defective-parts tray 10B is carried top slide in the X direction, a second sliding mechanism 22 which causes a table 22A on which a reclaimable-parts tray 10Cis carried to slide in the X direction, a third sliding mechanism 24 which causes a table 24A on which a satisfactory parts tray (or satisfactory-part replenishment tray) 10A is carried to slide in the X direction, and a transfer mechanism 26 which transfer the parts.
The conveying section 17 constitutes the conveying line. The front end of this conveying section 17 is adjacent to the rear end of the conveying section (not shown) of the inspection apparatus 16, and the inspected trays 10D are fed into the conveying section 17 from the inspection apparatus 16. After all of the defective parts and reclaimable parts contained in the trays 10D have been removed, satisfactory parts are replenished in the trays 10D. Then, the trays 10D filled with satisfactory parts are sent to the unloader stacker 18, where a plurality of trays 10D are stacked in a stack configeration. The conveying section 17 has a pair of belts 30A and 30B, and the trays 10D are conveyed using these belts 30A and 30B.
In the conventional example, the sliding mechanisms 20, 22 and 24 respectively have the same structure, and have a structure which causes the respective tables 20A, 20B and 20C to slide in a direction parallel to the conveying line (i. e., in the X direction). The transfer mechanism 26 transfers defective parts from the trays 10D to the defective-parts tray in accordance with the inspection results and likewise transfers reclaimable parts from the trays 10D to the reclaimable-parts tray 10C. Here, defective parts are semiconductor parts judged to be defective in the inspection of external appearance, and reclaimable parts are semiconductor parts judged to be re-utilizable or semiconductor parts judged to require re-inspection in the inspection of external appearance. Of course, it is also possible to handle all deficient parts (or defective parts) in the same manner. As a result of the removal of defective parts and reclaimable parts, one or more empty pockets are generated in the trays 10. Accordingly, these empty pockets are replenished with satisfactory parts from the satisfactory-parts tray 10A.
The transfer of parts between trays is accomplished by the transfer mechanism 26. In this conventional example, the transfer mechanism 26 comprises a suction chucking nozzle 28 which chucks the parts by vacuum suction, and a mechanism which moves the nozzle 28 in the direction (Y direction) perpendicular to the direction of the conveying line (X direction). The coordinates at which the parts transfer operation is performed are determined by the Y-direction position of the nozzle 28 and the X-direction positions of the respective tables 20A, 22A and 24A.
Thus, in the conveying apparatus 14 shown in FIG. 15, defective parts and reclaimable parts are removed from the trays in accordance with the inspection results, the trays are replenished with satisfactory parts, and the resulting trays filled exclusively with satisfactory parts are sent to the unloader stacker 18 and accommodated therein in a stacked fashion. The frequency of generation of defective parts and reclaimable parts is generally very low in each lot; accordingly, most of the trays following inspection flow "as is" along the conveying section 17 and are sent to the unloader stacker 18.
In the conveying apparatus 14 shown in FIG. 15, it is necessary to prepare the satisfactory-parts tray 10A at the beginning of each lot. Also, a fresh satisfactory-parts tray must also be prepared in cases where the initial satisfactory-parts tray becomes an empty tray at an intermediate point in the lot This will be explained below.
When the initial tray of a lot is sent to the conveying section17, defective parts and reclaimable parts are first removed from this tray. After this removal, the tray is tentatively sent to the unloader stacker 18; and at this point in time, an operator call is output. Afterward, when this tray is manually transferred to the table 24A by the operator, the apparatus is re-started, and conveying control similar to that described above is subsequently performed.
If the satisfactory-parts tray 10A becomes an empty tray at an intermediate point in this operation, an operator call is output in the same manner as described above. Afterward, the empty tray on the table 24A is first manually removed by the operator, and a tray that has been discharged into the unloader stacker 18 is manually transferred onto the table 24A.
Besides the above-described manual method, an automatic operation by means of successive transfer may also be realized. In this automatic operation, satisfactory parts are automatically transferred one at a time to the satisfactory-parts tray 10A from a tray 10D on the conveying section17 using the transfer mechanism 26 with the satisfactory-parts tray 10A in an empty state.
In such a manual operation, the operator must perform a manual tray exchange whenever a satisfactory-parts tray is required. As a result, considerable effort is required. Also, the operation is bothersome and inconvenient. If this operation is delayed, the interruption of conveying is extended so that the productive capacity of the production line drops.
On the other hand, in the case of the above-described automatic operation by successive transfer, the problems of bothersome manual work, etc. do not exist. However, since the satisfactory parts must be transferred one at a time, considerable time is required in order to transfer a large number of satisfactory parts. As a result, the productive capacity drops.
In a conventional apparatus, positioning of the parts at the time of pick-up and placement is accomplished by belt feeding of the trays. As a result, if the trays should slip on the belt, there is a danger of misalignment in accommodation of the parts on the trays.